The present invention relates to a water level control system for a reservoir.
In general, the apparatus for controlling the amount of water stored in the reservoir consists of a gate control apparatus which determines a desired discharging amount and a degree of opening the gate to materialize the desired discharging amount based upon a water level H measured by a water gauge which is installed near the discharge gate of the reservoir, such that a command for opening or closing the gate is supplied to a gate drive unit.
To maintain the stored amount of water and the water level at desired values, it is necessary to correctly detect the change of water level that is caused by the difference between the inflow rate and the outflow rate thereby to give a command of opening or closing the gate. However, the water gauge detects not only the change in water level caused by the difference between the inflow rate and the outflow rate but also detects transient fluctuation of the water level (hereinafter referred to as water-level noise) caused by the opening or closing of the gate or by the sudden change in the inflow rate. To cope with these problems, the conventional control system includes steps of detecting the water level by a water gauge after every predetermined period of time, and controlling the opening degree of the gate based upon the average value of the water level detected from a predetermined past moment through up to the present moment. Namely, the conventional control system relied upon a so-called running average method. With such a system, however, it was difficult to properly control the water level, overcoming the problem caused by the water-level noise. According to the above control system, therefore, when the inflow rate increased, the operation for controlling the opening degree of the gate often lagged behind proper time, and the degree of opening the gate tended to be greatly varied.